Study result
Parameter
Trays (base case)
Random packing retrofit
Trays at higher capacity
at higher capacity
Type of internal
Fixed valve trays (base configuration) 20 two-pass trays in stripping section; 3 single-pass trays in top wash section
IMTP#50 random packing
Fixed valve trays
in stripping section
(same as base configuration)
Arrangement
Trays 1–20 (stripping section)
Same as base case
replaced with packing (two beds × 5 m); top 3
single-pass wash trays kept.
Rich amine flow (m³/h) Reboiler pressure (barg) Reboiler temperature (°C) Pressure drop (mbar)
330 1.31 180 1.13 39.6 128.2
425 1.31
370 1.31 190 1.12 44.4 128.2
128.2
40
Top pressure (barg)
1.27
Steam flow to reboiler (MT/h) Steam amine flow ratio (lb./gal)
51
1
1
1
Lean amine H 2 S loading Maximum flooding (%)
0.0061
0.0067
0.0061
79
84
90
Table 1
millibar in the base case to just 40 mbar. This recovery in pressure is particularly noteworthy given that the total pressure drop across a typical SRU is approximately 1 bar. Such a gain in pressure head offers considerable advantages for downstream the SRU, which would require minimal modifications during revamp activities. In comparison, the pushed tray configuration achieved only a 12% increase in throughput, increasing flow from 330 cubic metres per hour to 370 cubic metres per hour. This performance was constrained by its flooding limit and resulted in a higher pressure drop of 190 millibar. As a result, the available pressure for the SRU is further reduced, needing more extensive modifications to accommodate the increased flow. Engineering considerations for tray-to- packing conversion While the performance benefits of packing are clear, successful implementation requires careful attention to the following factors: ○ Feed quality: Packed beds are less tolerant of solids and contaminants. Fouling can lead to costly maintenance, including complete packing replacement. Therefore, robust filtration systems are essential. Materials of construction should minimise corrosion, and operating temperatures must be controlled to prevent amine degradation. Upstream contactors should include effective
control to prevent hydrocarbon carryover, which can cause foaming and fouling. Corrosion inhibitors and proper metallurgy choice are also critical to minimising particulate generation. ○ Liquid and vapour distribution: Uniform distribution is essential for packed bed efficiency. Poor distribution can cause dry zones or flooding, reducing performance. High-quality liquid distributors and intermediate redistributors must be installed. Vapour distribution devices may also be needed to prevent channelling. These internals should be designed by experienced vendors familiar with amine service. Inadequate distribution can negate the benefits of packing, leading to poor separation and reduced capacity. ○ Operational discipline: Operators must watch for signs of maldistribution or fouling. Temperature profiles and separation efficiency should be tracked to detect issues early. Proper training and maintenance protocols are key to sustaining packed column performance. Routine monitoring of pressure drop, lean amine purity, and temperature gradients can help find developing issues. Preventive maintenance and periodic inspection of distributors are recommended to ensure long-term reliability. ○ Economic and operational impacts: The retrofit offers the following economic and operational advantages: Increased throughput : A 30% rise in rich
Refining India
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